To reduce errors in determining a degree of arousal due to variations in blinking among an individual or between individuals.To execute the steps of: acquiring first biological information related to an ocular potential of a user from a processing device worn by the user； and calculating a degree of arousal of the user based on a distance between a projection axis parallel to an equal degree of arousal line and a point where the first biological information is plotted in a coordinate space where a height and width are the axes for an ocular potential peak.
